I think you could tell your resolver to ignore checksums by setting the property to an empty String.
http://ant.apache.org/ivy/history/latest-milestone/settings/resolvers.html
Or you could define it globally by setting the attribute ivy.checksums to "":
From the Documentation (http://ant.apache.org/ivy/history/latest-milestone/concept.html#checksum):
For the moment Ivy supports the md5
and sha1 algorithms.
The configuration of using md5 and/or
sha1 can be done globally or by
dependency resolver. Globally, use the
ivy.checksums variable to list the
check to be done (only md5 and sha1
are supported). On each resolver you
can use the checksums attribute to
override the global setting.
The setting is a comma separated list
of checksum algorithms to use. During
checking (at download time), the first
checksum found is checked, and that's
all. This means that if you have a
"sha1, md5" setting, then if ivy finds
a sha1 file, it will compare the
downloaded file sha1 against this
sha1, and if the comparison is ok, it
will assume the file is ok. If no sha1
file is found, it will look for an md5
file. If none is found no checking is
done. During publish, all listed
checksum algorithms are computed and
uploaded.
By default checksum algorithms are
"sha1, md5".
If you want to change this default,
you can set the variable
ivy.checksums. Hence, to disable
checksum validation you just have to
set ivy.checksums to "".